WHOIS IP Lookup
Look up registration details for any IPv4 address. Find network ownership, organization, country, CIDR block, and RIR information using the RDAP protocol. A free tool by IPv4Center.
What Is a WHOIS Lookup?
A WHOIS lookup retrieves registration and ownership information for an IP address or domain. This includes the organization that holds the IP block, the Regional Internet Registry (RIR) it belongs to, the network range (CIDR), country of registration, and current status. WHOIS data is essential for network administrators, security researchers, and anyone investigating IP address ownership. Our tool uses the modern RDAP (Registration Data Access Protocol), which is the successor to the traditional WHOIS protocol, providing more structured and reliable results.
How Does WHOIS Lookup Work?
When you enter an IP address, our tool queries the RDAP servers maintained by Regional Internet Registries (RIPE NCC, ARIN, APNIC, LACNIC, AFRINIC). RDAP returns structured JSON data about the IP block, including the network name, managing organization, country code, allocation status, and relevant dates. Unlike the legacy WHOIS text protocol, RDAP provides standardized, machine-readable responses with proper authentication and access control.
Frequently Asked Questions
WHOIS is a protocol for querying databases that store information about registered IP addresses and domain names. It helps identify who owns an IP block, which organization manages it, and which RIR region it belongs to. This information is crucial for network troubleshooting, abuse reporting, and due diligence in IP address transactions.
RDAP (Registration Data Access Protocol) is the modern replacement for WHOIS. While WHOIS returns unstructured text, RDAP provides structured JSON responses, supports HTTPS, has built-in access control, and is standardized across all RIRs. Our tool uses RDAP for more accurate and reliable results.
You can look up any publicly routable IPv4 address. Private IP ranges (10.x.x.x, 172.16-31.x.x, 192.168.x.x) and reserved ranges will not return useful WHOIS data as they are not registered in public databases.
The status field indicates the current allocation state of the IP block. Common statuses include "active" (currently in use), "allocated" (assigned by an RIR to an organization), and "reserved" (set aside for specific purposes). The status helps understand whether an IP block is actively being used and how it was assigned.
WHOIS data is sourced directly from the Regional Internet Registries (RIRs) and is generally accurate. However, some records may be outdated if the registrant has not updated their information. For IPv4 transfer due diligence, we recommend cross-referencing WHOIS data with BGP routing data and blacklist checks.
Before purchasing IPv4 addresses, a WHOIS lookup helps verify the seller's ownership, confirm the correct RIR region, check the block size and range, and identify any potential issues. It is an essential step in the due diligence process for IPv4 transactions on our marketplace.